The genetic contribution to a number of neurological disorders is thought to be complex in nature, disease risk being driven by a combination of risk alleles commonly present in the human genome. Over the last 10 years we have invested considerable time and resources in applying genome wide association methods to determine the genetic basis of Parkinson disease. We formed the International Parkinson's Disease Genomics Consortium to facilitate international collaboration amongst leading Parkinson disease research groups focused on understanding the genetic basis of this disease. The most recent work performed by us and our colleagues is an extension of genome wide association in PD, to include a cohort of approximately 60,000 disease cases or disease-related cases, and 1.5 million controls. This work has revealed 90 risk loci for disease, has redefined the heritable component of Parkinson disease, has identified critical tissue and cellular context for genetic risk, and revealed co-morbid conditions.